The present invention pertains to apparatus and a method of correcting a phase/amplitude calibration in an adaptive monopulse system. While there are a variety of monopulse systems known in the art and it is anticipated that the present invention will operate on any of these systems, the present invention is disclosed primarily in conjunction with an adaptive monopulse system including phase/amplitude calibration circuitry and a receiver including dual channels providing elevation and azimuth output signals in response to a single input signal.
Monopulse systems generally include a rather complicated antenna and beam forming network which receive the single signal and generate a pair of output signals having relative amplitudes and phases that are dependent upon the direction of the received signal with respect to the monopulse system. The pair of signals are supplied to a two channel receiver which is pre-calibrated to provide elevation and azimuth output signals in response to the pair of input signals. Whenever a different receiver is substituted, or the operating frequencies are changed, the system must be recalibrated in a rather lengthy procedure. Generally, the system will be calibrated over an entire band of frequencies which further limits the accuracy at a specific frequency because the calibration is generally designed to provide the best results over the entire band.